Impact of Ablation Based Self Blast Nozzles on Load Break Switch Current Interruption Performance

In this contribution, SF6 free ablation assisted medium voltage load break switchgear, has been investigated. In these switches, gases generated by the arc polymer interactions are trapped in expansion chambers and are released back onto the arc at the current zero crossing. This increases the current interruption capability of the switch without the use of additional mechanical parts, as opposed to using a puffer to blow on the arc. Existing self-blast research, in medium voltage load break switchgear, has focused on blowing axially or tangentially onto the arc in a cylindrical arcing channel. More geometries are possible. In this paper, alternative self-blast blow-position and the presence of obstructions in the arcing channel have been investigated experimentally and with cold flow simulation. It has been determined that blowing right onto the arc centre is not optimal for cooling the arc, and that the presence of an obstruction in the arc channel is beneficial to arc interruptions